不同方位角下同軸對轉吊艙式推進系統之實驗研究

Abstract

隨著現代船舶推進系統對節能效率與操縱性能之需求日益提高，兼具推進效率與操縱能力之複合式推進配置逐漸受到重視。對轉螺槳可藉由後方螺槳回收前方螺槳尾流中的旋轉動能，以提升推進效率；吊艙式推進器則可透過方位角轉向產生側向力與操縱能力。然而，當後方吊艙式推進器操作於前方螺槳所形成之加速尾流與旋轉流場中時，前後螺槳間之水動力交互作用將顯著影響系統之有效推力、輸入功率、整體效率及轉向特性。本研究以同軸對轉吊艙式推進系統為研究對象，透過拖曳水槽模型試驗探討不同吊艙方位角下之水動力特性。實驗配置以前方螺槳搭配單獨螺槳動力計，後方則配置可進行方位角旋轉之吊艙式推進器。藉由量測不同操作條件與方位角下之推力、扭矩、縱向力與側向力，以評估系統之推進性能與操縱特性。實驗結果顯示，下游吊艙本體與上游支撐結構均會對螺槳水動力性能產生顯著影響，使其峰值效率相較於單獨開水域試驗條件下降。對於同軸對轉吊艙式推進系統而言，前後螺槳間之交互作用會明顯改變整體水動力特性與效率分佈，而前後螺槳之轉速比在高負荷操作條件下亦具有重要影響。方位角分析結果顯示，後方吊艙式推進器轉向後可產生顯著側向力與操縱能力。此外，正負方位角之轉向特性存在不對稱現象，顯示前方螺槳所形成之旋轉尾流會顯著影響後方吊艙式推進器之入流條件與轉向性能。整體而言，本研究結果證實，對轉螺槳與吊艙式推進器之間複雜的水動力交互作用，將共同主導系統之推進性能與操縱特性。

With the increasing demand for both energy efficiency and maneuverability in modern marine propulsion systems, hybrid configurations capable of simultaneously enhancing propulsive performance and steering capability have attracted considerable attention. Contra-rotating propellers (CRP) can improve efficiency by recovering the rotational energy contained in the upstream propeller wake, while podded propulsors provide maneuverability through azimuthal steering and the generation of lateral forces. However, when an aft podded propulsor operates within the accelerated and rotational wake generated by an upstream propeller, the hydrodynamic interaction between the two propulsors significantly influences the effective thrust, power consumption, overall efficiency, and steering characteristics of the system. This study experimentally investigates the hydrodynamic performance of a coaxial contra-rotating podded system under various pod azimuth angles using towing tank model tests. The experimental arrangement consisted of an upstream propeller mounted on a propeller open-water dynamometer and an aft podded propulsor capable of azimuthal rotation. Measurements of thrust, torque, longitudinal force, and lateral force were conducted under different operating conditions and azimuth angles to evaluate both propulsive and maneuvering characteristics. The experimental results demonstrate that the downstream pod body and upstream supporting structures significantly influence propeller hydrodynamic performance and reduce the peak efficiency compared with single open-water conditions. For the coaxial contra-rotating podded system, the interaction between the fore and aft propellers was found to strongly affect the overall hydrodynamic characteristics and efficiency distribution. The rotational speed ratio between the two propellers also played an important role, particularly under heavily loaded operating conditions. Azimuthal angle analysis showed that steering of the aft podded propulsor generated considerable lateral force and maneuvering capability. In addition, asymmetric steering characteristics were observed between positive and negative azimuth angles, indicating that the rotational wake of the upstream propeller significantly affects the inflow condition and steering performance of the aft podded propulsor. Overall, the results confirm that both propulsive and maneuvering performances are governed by the complex hydrodynamic interaction between the contra-rotating propellers and the podded system.